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Dec. 7, 1943.

R. s. T ROTT ENGINE MOUNTING Original Filed June 10, 1938 4 Sheets-Sheet' l INVENTOR.

D66. 7, 1943; s, Re. 22,403

ENGINE MOUNTING Original Filed June 10, 1958 4 Sheets-Sheet 2 3HLIVENTORL w 716.12. Z W

' Dec, 7, 1943. R, s; TROTT Re. 22,403

ENGINE MOUNTING Original Fil ed June 10, 1958 4 Sheets-Sheet 5 Hun In 2/V INVENTOR, I I l In 'Dec- 1943.v R. s. TROTT 1 ,4 ENGINE MOUNTINGOriginal Fi1ed Jfine 10, 1958 4 Sheets-Sheet 4.

INVENTOR.

Reissue d Dec. 7, 1943 Rolland S. Trott, Denver, 0010.;

Eleanor J. Trott cxecutrlx of said Rolland S. Trott, deceased OriginalNo. 2,249,194, dated July 15, 1941, Serial No. 212,887, June 10, 1938.Application for reissue .iuly 15, 1941, Serial No. 402,557

12 Claims.

My invention relates to engine mountings, and especially to enginemountings for radial'engines used in airplanes, and is a reissue of myPatent No. 2,249,194, granted July 15, 1941.

The object of my invention is to provide an engine mounting which willcushion all engine unit-forces, and thereby eliminate their transmissionto the airplane. I r

A further object is to provide an engine mounting which will cushioneachof the main sets of forces of the engine unit, without creating any.

new forces by such cushionings.

Further objects will appear during the following description.

Av statement regarding engine unit forces in their relation to presentradial engine mountings will make an understanding of my inventioneasier to grasp. I

In present radial engine mountings, the en- 'glne mount framework isattached to the fuselage of the airplane generally at four pointsimmediately in front of the fire-wall, and the engine is attached to thefront of this engine mount framework about two feet or more in front ofthe fire-wall, by about nine engine bolts on about a twenty-four inchbolt circle.

The four mounting bolts or pins on the firewall sometimes have thinrubber bushin s. an

. the engine bolts also may have circumferentially elongated rubberbushings.

But, regardlessof these and other details, present radial engine theirresults thatthe finger tips placed against any part of any airplane sofar built, will, when the engines are running, disclose that'the planeis being vibrated by the engine forces.

Many flying men even seem to think that in an airplane, engine,vibration is necessary, that it always has been present and always willbe present. There are at least four sets of engine unit forces which areat present responsible for the vibration of all planes.

These forces are as follows: 7 (l) The draft force, or-the pull ofthemepeller. (2) The tor ue force or reaction to the twisting of thepropel er.

ln'g parts, or to the movementsoi the pistons and connecting rods in aradial engine, or to result antsof the torque forces. (4) Forces due tothe engine unit weight, which puts the upper members of the presenttypeof mounting framework I mountings are so poor in (3) Transverse forces,or forces in planes normal to the crankshaft axis, and whichmay be outof balance forces due to out of balance in the propeller or othermovconnections in step with the slight gyratory or in tension and thelower members in compression.

The only way to cushion a force is to provide cushioning movement toabsorb the force, and this cushioning movement in an alrplanemust besuch as not to create any new forces, or the final results may be as badas, or worse than, the original forces.

In present engine mountings an almost rigid construction is employed. Insome there is a slight amount of rubber, as stated above, but thecushioning movements provided are really very small, too small to domuch good; and the reason 'for this is that, if more movement werepermitted, this cushioning movement would create new forces that wouldbe worse than the original forces if left uncushioned.

The facts regarding the four above-mentioned sets of forces are asfollows:

First: The draft jorce.-If there were no transverse forces operating,the draft of the propeller would perhaps come equally on all four enginemount connections with the fuselage.

at this actually can never occur. In a radial engine, the torque forces,the movements of the connecting rods and of the pistons,

the presence of out of balance in the propeller or other moving parts,or one blade of the propeller pulling more than another, will result intransverse forces and will create a condition which will tend to swingthe engine in a small circle or other orbit. As this slight swinging orgyratory movement takes place, the actual ,instantly acting draftconnection changes, in

- step with the swinging movements, so that each of the four connectionsof the engine mount with the fuselage, in turn is the actual momentarydraft connection.

Sothe draft on the plane is not a steady pull but is a pull whichtravels about the four draft swinging movement of .the engine due to thetransverse forces mentioned. This continual movement of the effectivedraft connection produces aierky pull or draft upon the plane which canonly result'in vibration in the plane. So,

though the actual pull of the propeller may be steady, the'action of thetransverse forces upon the draft force, results in an actual vibrationalat a speed of pull or draft force upon the airplane.

To illustrate: In a certain well-known nine cylinder 1000 horse-powerradial engine, the .vibratory force due to connecting rod movementspounds.

2160' revolutions per minute, is 1500 When this 1500 pound transverseforce is momentarily acting in the plane of two diagonally oppositetubular members of the engine mount framework, one of these diagonallyopposite members is subjected to compression and the 'pression, even ifa slight mount'of rubber is employed there is nothing in theconstruction to other diagonally opposite member is subjected totension.

Thus,- for this combination of draft force and transverse force, themore transverse cushioning movement permitted in present type mountings,the greater would be the result upon the draft force and the greaterwould be the vibration due to shifting of the actual momentary draftconnection. v

That is, new forces would be created.

In my invention, this movement of the draft connection and the resultingwibration is overcome by a single centrally located resilient draftconnection, which provides steady and non-vibrating pull or draft uponthe plane, in spite of all transverse cushioning movements of the engineunit.

Second: The torque forces.-In the abovementioned 1000 horse-power engineeach cylinder is more than six inches in both bore and stroke, and eachcylinder develops a maximum of 111 horse-power.

So, when such a cylinder fires, there is a great torque shock, tendingto oscillate the engine in a direction opposite to the direction ofrotation of the propeller.

The only way this torque shock can be cushioned is by torque cushioningoscillation. But, this torque cushioning oscillation must take placewithout creating any newforces.

The rotationof a perfectly balanced flywheel can take place without thecreation of any new forces; but if the flywheel is unbalanced therotation of the flywheel will create tremendous new forces. i I

This holds just as true about the oscillation of a balanced flywheel; itcan take place without the creation of any new forces. oscillation of anunbalanced flywheel will create new forces. But, in a flywheel, theweight only, has to be considered. In a balanced flywheel, the axispasses through the center of mass of the'flywheel, and this is enough toavoid the creation of any new forces.

But, in a radial engine, this is not enough. Not only the center of massmust be considered, but also the propeller, and the draft connectionbetween the engine unit and the plane.

So, in my enginemounting for airplane engines, the axis is so locatedthat it passes through the center of the propeller hub, through thecenter of mass of the engine unit, and through the single draftconnection of the engine unit with the plane.

That is, in my invention torque cushioning oscillation of sufficientamplitude is accomplished without movement of the propeller, the centerof mass, or the draft connection with the plane, by.

so mounting the engine unit as .to provide and maintain an axis ofoscillation that passes through the center ofthe propeller hub, throughthe center of mass of the engine unit, and through the single, centrallylocated draft-connection.

When this is done, sufiicient torque cushioning oscillation may beprovided to properly cushion the torque jerks of the big cylinders andwithout creating any new forces from any cause whatever, because of theabove-mentioned location i of the axis 'of oscillation.

In present radial engine mountings, the lower members of the mountframework are in comcate and maintain any particular position for anaxis of oscillation, and if any slight oscillation does take place theaxis for this oscillation is probably at or near the level of the lowermembers of the mount framework, which would locate the propeller hub andthe center of mass considerably above such as axis.

Thus, in present type mountings, the greater the amplitude permitted intorque cushioning oscillation, the greater will be the forces createddue to unbalance of the oscillation both as regards the center of massand as regards the center of the propeller hub. I

, Ample torque cushioning oscillation with present radial enginemountings would be like oscillating a flywheel with an off-center shaft.

For this reason, present radial engine mountings are, and must be,substantially rigid.

Also, any oscillation with present mountings,

.slight though it may be, can not take placeabout an axis passingthrough thedraft connection with the plane, since the actual draftconnection, as explained above, revolves about the four points ofattachment with the plane, as the engine swings or gyrates, in answer tothe transverse forces.

My axis through the, center of the propeller hub, through the center ofmass and through i .the single draft connection, is the only solutionthat will permit the proper and necessary amount of torque cushioningoscillation without creating new and very destructive forces.

Oscillation that would move the propeller hub, the center of mass or thedraft connection, with respect to the engine unit, would createnew anddestructive forces.

Thus in the present type of radial engine mountings, the more torquecushioning oscilla-- tion permitted the greater would be the vibrationdue to the off-center position of the propeller, the center of mass andthe draft connection, which in present type mountings is not stationary.

That is, in present type mountings, if ample torque cushioningoscillation new forces would be created.

- Third: Transverse forces.-These forces as mentioned above, combinewith the draft force, to provide a jerky, rotating, four-point draftconnection between the engine unit and the fuselage, one point at a timebeing the momentary, main draft connection.

were permitted,

These transverse forces, in the present type of radial engine mounting,tend to put tension successively on each of the four points ofattachment with the fuselage and to add to the draft force at one pointwhile tending to put the diagonally opposite frame member incompression.

If the engine unit were in perfect running balance and had no transverseforces and were mounted to oscillate about a longitudinal axis passingthrough the center of the propeller hub and through the center of mass,a single central draft connection might not be needed and might givelittle benefit-if used. But, as a matter of fact, no engine 'is in andall engines have transverse forces. So, my

' single central draft connection is necessary, if

a vibrationless draft force is to be delivered to the plane.

Suppose we now consider another condition with the crankshaft. say,slightly out of balance;

perfect running balance,

this will change the actual location of the center of mass of the engineunit, providing a new center of mass, and the drankshaft will'tend torevolve about a new axis passing through this new center of mass.

a If the engine unit is mounted freely enough to permit this new axis toact as the actual axis,

then the engine will still run in perfect balance,

' but the former axis will revolve about this new axis.

Or, if the engine case is now made out of balance with respect to thisnew axis, this also willpermitted the engine to cushion the transverseforces may take place without creating any new forces. 4

So, the same single, central attachment principle which permits a steadynon-vibrating draft also permits the transverse cushioning move- ,mentsof the engine unit about a single central rear mounting without creatingany new forces, by such movements.

- In some cases the rear mou ting may also act as the single centraldraft connection, but I do not favor-this for the really large engines.

Thus with transverse forces, if enough cushioning movement is'provided,new forces will be created due to the four point connection in presenttype mountings. with the firewall. These forces are independent of thedraft force, but when they are combined with the draft force the resultsare very much greater.

Thus, in present mountings increase of transverse cushioning movementscreates new forces. Fourth: Weight forces-4n present mountings theweight of the engine is carried by the framework with part of themembers in tension and part of the members in compression. This puts theengine weight entirely out of balance and very top-heavy, as far as anytorque cushioning oscillation is concerned, as was explained above underTorque forces. Since the weight is not located so that it can remainunmoved during engine oscillation, the weight forces wo'uld generate newforces if ample oscillation were permitted to properly cushion thetorque forces.

It may be that some of the above-mentioned four sets'of forces tend tooverlap; but it is thought the above explanation will at least make thematter clear to any mechanic versed in this At any rate it is now clearthat in present radial engine mountings cushioning movements of any kindwilltend' to create new forces which verypossibly might be originalforces. I

Thus in present type mountings, every attempt to provide a really amplecushioning movement for any force has had to, be abondoned, and this hasresulted in mountings whose cushioning movements are so slight as toamount to substantially rigid mountings.

more destructive than the I attachment to the engine,

sion for the engine (which may be designed either as an integral part ofthe engine, or as an as shown in the draw-' ings) and locate the enginepartly by the rear mounting, which is located at the rear end of thisextension, and partly by the front mounting which is located adjacentthe rear of the engine proper, so thatthe engine weight is carried'attwo longitudinally separated points.

If the weight distribution of engine and accessories remains the same asat present, the

rear mounting point will carry a negative load,

and the front mounting point will carry more than the weight'of theengine, in load. Though it is possible to redistribute engine andaccessory weights so the rear mounting will carry a positive load, itwill generally be found to be unnecessary. "The two mountings maintainthe proper axisof oscillation, which passes through the center of thehub of the propeller, through the center of mass of the en gin'e unit(even if redistribution of weight is required for this), and through thesingle central draft connection between the engine unit and thefuselage.

when the propeller is offset from the crankshaft, in which case aredistribution of engine or accessory weights may be necessary in orderto locate the center of 7 mass on. the axis.

My engine unit consists of the propeller, the engine, and accessories,and the rearward extension which carrles the rear mounting. I

All necessary controls'ahd connections are to be so constructed andarranged as to permit all. of the engine cushioning movements withoutfailure in their functions.

-What takes place in my method of cushionin out of balance haps best beillustrated by wooden top. When new, if

reference to a boy's properly made, the

-- top will spin in perfect balance about what may be called itsgeometric axis. It should be noted that the top has but one mounting,the rear mounting, where the peg is centered on the ground. but the topits upper end, where move transversely, It finds the axis which passesthrough its center of mass.

If a chip issplit from one side of the top. the center of mass will beshifted away from where the chip was taken.

finds its own axis because this new center of mass, and the former axisthat was called the geometric axis, will then revolve about this newaxis. The too will appear to wobble. but except for wind resistance itwill be as perfectly balanced as before. because it -is free to findthis new axis and revolve about it. on

In my mounting I provide a comparatively unloaded and comparativelystati0nary rear mounting. and a front mounting'wh ch carries most of theweight and provides most ofthe transverse cushioning movements.

By this construction, 'the engine tivelv free to find its own ax s andrevolve and oscil ate about It in much the same manner as inthe case ofthe topv abovementioned.

In my invention rubber so constructed and arranged as to car y eitherpositive or negative load resiliently, resil-' iently resistoscillation'of the engine unit, and resisiently resist any longitudinalmovement of the engine unit, and to permit universal move- In myinvention I provide a rearward exten- [5 at,

locate and geared, it is sometimes Y or transverse forces; can perallthe weight is, is free to Then when the too spins. it will spin about anaxis that passes through is compar'athe rear mounting includes 7 Thefront mounting consists in metal mounting means adjacent the rearpf theengine so constructed and arranged as to locate the axis of oscillationto pass through the center of the rear mounting, through the center ofmass of the engine unit and through the center of the hub of thepropeller. means may be a plain metal bearing, or any type or kind ofanti-friction bearing, or may be an' outer metal track cooperating witha series of anti-friction bearings mounted on the nine engine bolts onthe 23% inch diameterbolt cir- This metal mounting.

cle, or may be an inner track cooperating with a series of antifrictionbearings properly supported, all of which. will be clearly understoodbyany mechanic versed in this art.

For, whatever the kind or type of metal bearing means employed, theresult will be the same in that the center of this front metalbearingmeans positively locates the axis of oscillation in the'plane ofthis bearing means. That is, re-

gardless of what else takes place, any oscillation that takes place musttake place about the axis located by this metal bearing means andtherear mounting on the fuselage; and these two mountings are soconstructed and arranged as,

to make said axis pass through the center of mass and the center of thehub of the propel- 181; ing also may act as the single central draftconnection, this axis will also be located to pass through the center ofthe single central draft connection,

a The front metal mounting means, of whatever construction, is carriedby a proper rubber cushion or other proper resilient means, to provideSince for smaller engines the rear mountfor the proper cushioning of alltransverse forces and for the self-centering action mentioned above.

This front mounting cushion means, of whatever construction, is properlycarried in a framework, similar to the present engine mount, andattached in a similar manner to the fuselage directly in front of, thefirewall.

In my construction the rear mounting carries much less weight than thefront mounting since it is more remote from the engine cylinders and thecenter of mass.

This construction permits the same kind of self-centering action forperfect balance, as illustrated above in connection with a boy's top.,

There is, however, this difference; the top has only rotation; theenginex has both rotation and oscillation, but the self-centering willtake place in the engine very much like it takes place in the top.

The details of construction of my invention will be better understood byreference to the drawings, in which:

Fig. 1 is a side view in partial section, of my engine mounting, andwith some of the meeting parts of the plane, and with the engine andpropeller indicated;

ported by the tubular ring l9.

Fig. 7 is a sectional view of the outer ball race of the-front mounting;

Fig. 815 a side view of Fig. 7;

Fig. 9 is an end view of the rear mounting thrust plate;

Fig. 10 is a sectional view of Fig. 9;

Fig. 11 is a view in partial section of a modified form of the rearframework to carry the rear engine support;

Fig. 12 is a detail showing a modified form of connection of the frontframework and oil the rear framework to. the fuselage, adjacent thefirewall;

thefront framework and of the rear framework with the fuselage, adjacentthe firewall;

Fig. 14 is a modified .form of connection be-. tween the front frameworkand the rear framework;

Fig. 15 is a fragmentary detail showing a modified form of constructionof the inner ball race of the front mounting and the front outriggerring.

The engine outrigger or extension is provided with an innerball race 2,which is provided with nine engine fitting bolt holes 3, for securelybolting the outrigger to the rear of the engine by the same bolts whichin present engine mountings mount the engine upon the framework that iscarried upon the front end of the fuselage.

The ball race 2 has securely welded to it, with proper gussets andreinforcements, the tubular members 4.

The ring 20 is properly welded to and sup- The outer wall race 2| isplaced about the inner, ball race 2' before the outrigger is bolted tothe engine, and

the notches 26 of the two races are made'to register with each other.The balls 22 are then fitted in ,between the two ball-races, through theregistered notches and when the balls are all in place the outer race isturned 180 degrees,

so that the notches 2.6 will no longer register with each other, whichprevents any of the balls from getting out'of place from between theraces.

The ball race rubber cushion 23, and the retainer ring24 are then putinto place about the outer ball race 2|, and the outrigger is thenproperly bolted to the engine. I

The rear rubbers 9 are put into place between the abutments i4 and theend plates l2 and i3 Fig. 2 is a front view looking toward the airplane,of the main parts'of my mounting shown in Fig. 1, for supporting theengine unit upon .and 5;

of the rear frame ring i l.

The engine unit is then ready in its framework.

The ring 5 and its abutments 6 are located to slide in between therubber cushions 9, while the ball bearing rubber cushion 23 slides intothe ring 20. The retainer ring 24 is then properly bolted to the ring 20and the tubular ring l9, thus clamping the rubber cushion 23 in place,and the thrust plate III is properly attached and locked to the ring 5the rubbers 9 in place.

a The entire engine unit and its framework may now be properly attachedto the airplane at its four clevises l6, the-four pins or bolts passingthrough the clevises i6' and the airplane yokes just in front of thefirewall 25. In some cases rubber bushings may be used for the pins orbolts. i

In the mounting thus far described,'it will be seen that the rearrubbers 9 combine with the rest of the rear mounting construction toprovide or permit universal movement, to resiliently transmit the entiredraft of the engine unit to Fig. '13 is a modified form of connection a!to be mounted thus clamping the plane and to resiliently oppose torquecushioning oscillation about the axis which passes through the center ofthe Single draft connection, through the center of the front mounting,

through the center of mass'of the engine unit,-

and through the center of the hub of the propeller; while the frontmounting'maintains the axis in its proper location and provides ampletransverse cushioning for the transverse forces. It should be especiallynoticed that in order to have all the draft taken at the rear singlecentral draft connection, the retainer ring 24 should have the properslight amount of clearance with the rubber cushion 23, though this isnot clearly shown in the drawings.

For planes with comparatively small engines the mountingthus fardescribed may be in most The plane draft wrist-pin 33 is properly heldin place in rings that are gusseted and reinforced in the planeframework as indicated at 34, or

- otherwise.

cases sufficient; that is, the entire draft and the entire torque istaken through the rubbers 9 of the rear mounting.

The draft will be delivered through the thrust plate Ill to the rubbermembers 5 and to the rear frame ring H.

When the transverse forces are cushioned by the cushion ring 23, causingtransverse gyrations Ofthe engine, still the draft will be unchanged,and will be transmitted to the plane through the rubbers 9 of the singlecentral draft connection provided by the rear mounting. But, while thetransverse and draft forces are thus being properly cushioned, each timea cylinder fires there is a torque force.

This torque force will tend to oscillate the engine unit about the axisprovided by the front and the rear mountings, and this oscillation willbe resiliently opposed by the rubber cushions 9 cooperating with theabutments '6 of the rear engine ring 5 and with the abutments M of therear frame ring H.

But since this oscillation takes placeabout the axis provided by the twomountings, its amplitude is of little consequence, so long as it issufllcient to properly cushion the torque shock, and so long as allengine controls and connections are properly designed and built topermit such oscillations and transverse cushioning movements withoutaltering their actions. That is, all engine unit 7 controls andconnections are to be so constructed and arranged as to permit allengine unitmovements without change in the performance of said controlsand connections, as any mechanic versed in the art will understand.

Since the torque cushioning oscillation takes place about an axispassing through the single draft connection, through the center of mass,and through the center of the propeller hub, no

new forces whatever will be created by this oscil-.

lation. i

It should be noted that the entire engine unit and framework may beremoved from the plane exactly as is the case with present typemountings; that is, simply by the removal of the four clevis bolts justin front of the firewall.

It should also be noted that if desired, removal of the bolts of thethrust plate Ill and of the bolts of the retaining ring 24 will permitthe engine unit to be removed from the engine supporting framework,leaving the engine supporting framework attached to the plane.

Itshould also. be noted that removal of the nine engine bolts whichattach the outrigger to the engine will permit the engine to be removedfrom the outrigger, and from the plane.

In case the mounting is used for a large and plane.

The wrist pin 33 is-held in place by the bolts and nuts 32, similar tothose holding the wrist pin 3 l in place.

as any mechanic versed in the art will under-' stand.

It will be noted that the axes of the wrist-pins 3i and 33 cross theaxis AA at right-angles to each other. The draft and torque spring 35,has an eye at each end supplied with a rubber bushing 33,. whosethickness and consistency will determine the amount of resilience in thedraft connection. This spring 35 is twisted degrees, so that its endsmay be received by the wrist-pins 3| and 33-.

The pivotal movements at the wrist-pins, the cushioning of the rubberbushings, and the twist of the spring 35, combine to make certain thatno uncushioned vibration may be transmitted by the spring 35 from theengine unit to the airplane. This construction acts to reinforce thesingle draft connection and the resilient torque opposition of the rearmounting.

Though the width and thickness of the spring 35 should, of course, bedesigned for the particular engine served, it may be from an eighth to jthree-eighths of an inch thick, and from three to six inches wide andtwenty or more inches Fig. 11 illustrates a modified form for thesupport upon the airplane, of the rear mounting of the'engine unit. 1 c

The flange of the firewall plate 25 'may be bolted to either the frontor the rear faceof the firewall proper. Itis supported in the rear framering II, which in turn is properly supported by r the tubular frameworkmembers I5, or otherwise. The front plate i2 is properly bolted to thefirewall plate 25f and to the rear frame ring II. This separate firewallplate may, of course, be

used in the Figure l construction, if desired,

either with or without the spring 35.

. When the en'gine unit is removed from the airplane with this rearmounting support construction, the front plate I2 is removedin any case,whether the front framework is left attached to the plane or not, andthe front framework may be removed from the plane by removal of the fourclevis pins, or the engine may be removed from .the front framework byremoyal of slight addition may be made which attach the outrigger to theengine. For large engines-a draft and torque spring should be used withthis rear mounting.

"Fig. 12 is'a modified form of construction by which the front frameworkand the' rear framework may be joined together detachably, instead ofpermanently.

The front framework clevis I6 is straddled by the rear framework clevis40, and the same long clevis pin passes through both clevises and theairplane framework yoke.

In Fig. 13 still another modified form of mounting the front and therear framework is shown. The front framework clevis IE is mounted on itsyoke by its pin in the usual way. and the rear framework clevis 4| ismounted on the airplane framework and yoke by an entirely separateclevis and clevis pin.

Fig. 14 shows a modified form for joining the front and the rearframework detachably instead of permanently.

The clevis 42 is joined by the pin 43 with the clevis yoke 44 of thefront framework, and the the retainer ring 24; or the engine alone maybe removed by removal of the nine engine bolts propeller hub, the centerof mass, and the draft.

' connection.

- and permitting all necessary force cushioning clevis l6 of the frontframework is mounted in the usual way upon the airplane framework andyoke. I

Fig. 15 shows a modified form of construction for the innerball-race-and front ring of the outrigger.

Theinner race 2' ismade entirely separate fromthe ring 50. The ring 50has a flange 5| which actsto clamp the race 2' against the engine.

In this construction the inner ball race may easily be replaced whenworn without the necessity of replacing the front ring of the outrigger.

It will now be seen that my invention consists in a construction inwhich the draft connection means of the engine with the plane is at asingle point, remote from the cylinder portion of the engine.

This drafirconnection means may be at the rear of an outrigger, asshown, or the engine and accessories may be designed to extend the rearof the engine and take the place of the outrigger. The essential pointis that whatever the details of construction, the rear resilientmounting of the engine unit, which acts as the draft connection means ofthe engine .unit with the plane,

should be spaced considerably to the rear of the 7 engine cylinders.

The draft connection means may be attached to the plane to the rear ofthe plane of the present firewall as shown; or it may be right at thefirewall line, or if desired may even .be in frontof the firewall.

But, however these details are constructed, the draft connection meansshould also include resilient means acting to support positive ornegative'load and to resiliently oppose the torque Thus the pull of theengine on the plane will be steady and acting upon one point, and yetthrough resilient means the torque forces may be cushioned by plenty oftorque cushioning oscillation without creating any new forces, and thetransverse forces may be cushioned by transverse cushioningmovementswithout trans- 'mitting such movements to the plane or creatingany new forces.

Naturally, there are many changes that can be made in my'inventionwithout departing from the essence thereof, which consists of aresilient, single, central draft connection means between theengine unitand the plane, and engine supporting means supporting the engine on theplane movements about the draft connection or about the axis passingthrough the draft connection as a center, whether the resilient-draftand the resilient torque connections between-some part of the engineunit and some part of the plane are entirely of rubber or are of rubberand steel.

Thus it will'be seen every force that might be transmitted from theengine unit to the plane, can, in my mounting, only be transmittedthrough resilient members, and the construction is such that the.cushioning movements can be so calibrated or designed into theconstruction as to provide such cushioning for. every engine force thatthe senses will not be able to perceive them;

. and these cushioning movements, will none of them create new forces,

It will be appreciated by anyone versed in the art that many variationsare possible in the construction details ofthe particular structuresillustrated, and that also be made in my method without departing fromthe essence thereof.

It will also be appreciated that, though my invention has been describedmainlyin connection with a nine cylinder radial engine, it will operateequally well with a seven cylinder or a double row fourteen cylinderradial,.or any other kind, type, or construction of engine, ,if the sametheories andunderstanding were employed by a competent mechanic versedin the art.

This description deals especially with airplane engines with thepropeller in front, but is just as true if the engine were mounted in aZeppelin. Any mechanic versed. in the art will understand that themethod, the principles and even the details of construction will applyequally well in Zeppelin or airplane engines with the propellers totherear of the engines, with only such necessary changes as a mechanic willreadily understand. So, I do not wish to be limited to the exactcushioning oscillation of the engine unit, while,

at the same time permitting any and all force cushioning movements ofthe engine unit, without movement of the-point-of draft of the enginewith the plane.

Any other'set ofdetails of-construction than those shownfor properlysupporting the front engine mounting upon the plane and permitting forcecushioning movements in any direction may be employed, so long as thetorque cushioning oscillation takes place about the axis of oscillationpassing through the center of the porting means what I claim as new anddesire to protect by Letters Patent is as follows:

1. In an airplane engine and propeller unit mounting, movable draftconnection means be tween the said unit and the plane, spaced remotelyfrom the cylinder portion of the engine unit, and compound supportingmeans longitudinally spaced toward the engine cylinders from said draftconnection means, said compound sup- ,comprising resiliently mountedrotary bearing the said unit on nent oscillatory movement about an axisand combining with said draft connection means to provide a single axisof oscillation about which said unit may oscillate in balance at alltimes and various slight changes may means for resiliently supporting.the plane for continual, permanection means and of longitudinallyextending under all conditions, and said draft connection a hollowskeleton cylinder, the outer portions-of the said elements fitting intolongitudinally extending grooves in a member carried by said airplane,and the inner portions of the said rubber elements fitting intolongitudinally extending grooves in a means carried by said engine.

2. In an airplane engine and propeller unit mounting, movable draftconnection means between the said' unit and the plane, spaced'remotelyfrom the cylinder portion of 'the engine unit, and compound supportingmeans longitudinally spaced toward the engine cylinders from said draftconnection means, said compound supporting means comprising resilientlymounted rotary bearlng means for resiliently supporting the said unit onthe plane for continual, permanent oscillatory movement about an axisand combining with said draft connection means to provide a single axisof oscillation about which said unit may oscillate in balance at alltimes 'and'under all conditions, and a torque member composed of alongitudinally extending leaf steel spring movably coni nected at oneend to the engine and the other end to the airplane.

3. In a mounting foran airplane engine and propeller unit, an extensionacting'as a part of the engine to form a unit therewith and extendingsubstantially concentric with the engine crankshaft, mounting meansattachingthe end of said extension remote from the engine to theairplane and providing asingle movable conproviding for resilientlyopposed movements between the extension and the V airplane in anydirection, mounting means adja cent the other end of the extensionand'supporh ing the said um't including oscillatory, axis-locatingmeans, said rotary bearing means to provide for and maintain a singleaxis of oscillation about which the engine and propeller unit mayoscillate in bal-' ance at all times, and said mounting means remotefrom the grooves, a series of rubberelements fitting in said grooves,and said elements surrounded by and received in a series of longitudinalgrooves provided by a mounting element carried by said airplane. 4. In amounting for an airplane engine propeller unit, an extension acting asapart of the engine to form a unit therewith and extendconcentric with,the engine ing substantially on, the airplane and providing forcushioning movements in any direction and pound supporting meanslongitudinally spaced toward the engine cylinders from said draftconnection means, said compound supporting means comprising aresiliently mounted anti-friction bearing which providesfor freeoscillation of the engine for resiliently supporting the said unit onthe plane for oscillatory movement about an axis and combining wi h saiddraft connection means to provide a single axis of oscillation aboutwhich saidunit may oscillate in balance at all times and under allconditions.

6./In a mounting for an airplane engine and propeller unit, an extensionacting as a part of the engine to form a unit therewith and extendingsubstantially concentric with the engine crankshaft, extension mountingmeans attaching the end of said extension remote from the engine to theairplane'and providing a single movable connection means and providingfor resiliently unit.

' 7.. In an 'airplane and propeller unit, unit 5 mounting means formounting said unit, upon its engine being provided with .a seriescrankshaft, mounting means attaching the end of said extension remotefrom the engine to the airplane and providing a single movableconnection means and providing for resiliently opposed movementsbetweenthe extension and the air- 1 lane in any direction, mountingmeans adjacent the other end of said extension and supporting thesaidunit on the airplane and providing for cushioning movements in anydirection and including oscillatory, axis-locating means, said rotarybearing means to provide for and maintain a single axis of oscillationabout which .the engine and propeller unit may o cillate in balance atall times, and a torque member composed of a longitudinally extendingleaf-steel spring movably'connected at one end to the engine and theother end to the airplane.

.mounting means combining resiliently mounted which the engine plane andconsisting of front mounting means having a metallic axis-locatingpivotal portion and a shock cushioning portion surrounding the latter,cushion rear mounting means similar to the frontmounting mean said frontmountin means comprising a resiliently mounted anti-'- friction hearingwhich provides for free oscillation of the engine about an axisextending approximately through the longitudinal center of .the unit,and torque cushioning means not acting to disturb the cushioning actionsof the front and rear mounting means, said front and rear mounting meansbeing constructed, arranged and located to pass the axis of oscillationthey provide through the center of mass of the propeller, and throughthe center of mass of the engine.

8. .In an 'airplane engine and propeller unit mounting, a single draftconnection between the engine unit and the viding forresilientlyresisted movement between the draft connection and the plane in anydirection, including universal movement and oscillatory movement, andfront mounting means lo'ngitudinally spaced from said draft connectionand supporting the engine unit upon the plane for cushioning movementsin any direction, said front mounting means having metallic pivotalmeans for providing free oscillation of the engine about a positivelylocated axis and resilient means supporting said metallic pivotal' meansupon said plane. a

.9; Mounting means for an engine, includinga metallic axis-locatingbearing surrounding apart of'the engine and connected with the. body inis. located, said mounting means comprising a resiliently mountedanti-friction bearing which provides for-free oscillations of theplane,': mounting means proengine about an axis extending approximatelythrough the longitudinal center of the engine, and

. rubber held in shear between an extension from the engine and aportion of the body to resiliently restrain oscillations of the engine.

10. Mounting means for airplane engines comprising a cushioned,metallic, anti-friction bearing secured to the airplane frame andsurroundinga part of the engine and providing for free rotary motionabout the crank-shaft axis. under the influence of torque impulses, butresiliently resisting longitudinal movements and movements transverse ofthe crankshaft axis, an extension on said engine, and a; resilientmounting disposed between said extension and the airplane frame actingthrough shear to resiliently restrain rotary motion of said engine.

11. Mounting means for an airplane engine comprising a, cushioned,metallic, anti-friction bearing secured to the airplane frame andsurrounding a part of the engine and providing for free rotary motionabout an axis under the infiuenee of torque impulses, but resilientlyresisting longitudinal movements and movements mounting locatedlongitudinally remote from said bearing and constituted by twoconcentric elements, one of which is connected with the engine and theotherwith the airplane frame, with a medium therebetween acting throughshear to resiliently restrain rotary motion of said engine.

transverse of the crankshaft axis, and a resilient 25 12. Mounting meansfor airplane engines including in combination with an engine, apropeller, driven thereby, an extension from the en:- gine connectedwith the airplane frame, mount ings located at each end of theextension, one

mounting secured to the airplane frame and surrounding a part of theengine providing for free rotary motion about the crankshaft axis underthe influence of torque impulses, the other mountt ing located at theouter end of the extension and resiliently resisting longitudinalmovements as well as movements transverse to the crankshaft axis, thetorque cushioning oscillation taking place about the axis of oscillationpassing through the center of the propeller hub, the center. of mass ofthe engine, the center of the two mountings, and the center of the draftconnection with the airplane. ROI-LAND S. TROTT.

